Cutting device for sewing machines



CUTTING DEVICE FOR SEWING MACHINES Filed June 20, 1966 Sheets-Sheet l .J- fr0/7626 I? Tambur'ro April 30, 1968 F. P. TAMBURRO CUTTING DEVICE FOR SEWING MACHINES 4 Sheers-Sheet 2 ,flL/ ll l Filed June 20, 1966 'INVENTOR Ffa/7G65 P Ta/vbarro HTTONEY F. P. TAMBURRO CUTTING DEVICE FOR SEWING MACHINES April 30, 1968 4 Sheets-Sheet 3 Filed June 20, 1966 t INVENTOR. )Wa/vaas P Tambu/r'o 7 BY Z WM M /7 H77' 0 April 30, 1968 F. P. TAMBURRO CUTTING DEVICE FOR SEWING MACHINES 4 Sheets-Sheet 4 Filed June 20, 1966 NVENTOR. FP6/762 6 P 70mm/fr0 HTTOENEYJ United States Patent O M 3,380,417 CUTTING DEVICE FOR SEWING MACHINES Francis P. Tamburro, Teaneck, NJ., assignor to Willcox & Gibbs Sewing Machine Company, New York, N.Y., a corporation of New York Filed June 20, 1966, Ser. No. 558,957 Claims. (Cl. 112-252) ABSTRACT OF THE DISCLOSURE A cutting device for sewing machines having a movalbe blade pivotally mounted on an adjustable base member to provide accurate positioning of the movable blade and the shear angle and is separate from the fixed blade so as to leave a clearance around the fixed blade so that material can be fed thereover without interference. The movable blade is carried on a floating carrier and is yieldingly urged into accurate contact with the fixed blade throughout the entire shearing action with a required shearing pressure.

Heretofore efforts have been employed wherein a fixed cutter block had a chopper blade which was moved into cooperation therewith to sever the chain. Also, it has been proposed to use a pair of pivoted shear blades, which pair of blades is moved from a retracted position to a cutting position when it is desired to sever the chain. Neither of these have been entirely satisfactory for severing the chain formed at the sewing station.

The present invention overcomes these difficulties by providing a fixed blade carried by the sewing machine frame and a pivoted shearing blade cooperating therewith, said blades being disposed behind the sewing station of the sewing machine with the pivot point for the movable blade laterally displaced and preferably separate from the fixed blade. The movable blade is normally held in a raised position whereby there is an unobstructed passage for the material passing through the cutting device frorn the sewing station. This is of particular advantage in an otf-the-arm machine wherein the garment surrounds the arm.

A feature of the invention resides in the simplicity of the construction and in the ease with which adjustments of the movable blade with respect to the fixed blade can be made to accomplish the accurate positioning, shear angle and shearing pressure and to accommodate variations in manufacturing tolerances.

Another feature of the invention resides in the fact that the movable blade is carried by a carrier and is capable of being easily removed for sharpening and remounted in the same position after the sharpening, as it occupied prior to the sharpening operation so that its cooperation with the fixed blade is not altered.

A further feature of the invention resides in the construction of the device which enables it to be readily mounted on new or existing machines with a minimum of modifications to said machines.

Other features and advantages of the invention will be apparent from the specification and claims when considered in connection with the accompanying drawings in which:

FIGURE l is a front view of the novel cutting device of the present invention.

Patented Apr. 30, 1968 FIG. 2 is a side view.

FIG. 3 is a top view.

FIG. 4 is a sectional View taken along line 4 4 of FIG. 2.

FIG. 5 is an enlarged detail View of the cutting blade and its movable operating means.

FIG. 6 is a section taken along line 6-6 of FIG. 5.

FIG. 7 is a view showing the cooperative relation between the movable and fixed blades.

In the illustrated form of the invention, a cutting device 10 is secured to the frame of a sewing machine 11 by a screw 12 with the forward end of the device mounted on the usual pivot post 13 for the usual foot lifter mechanism 14 which is secured to the frame as shown in FIG. 3. The foot lifter mechanism 14 is pivoted on the post 13 and has a forward extension 14a for engaging under the usual presser foot of the machine and has an arm 14b at the other side of the pivot for actuating the lifter to raise the presser foot.

The cutting device has a plural part base 15 herein illustrated as embodying three elements: one is an actuating shaft carrying stamping 16 which is secured to the base by the screw 12 (FIG. 3), another is a pivot carrying casting 17 carrying the pivot for the movable blade, and the third is a bracket 18 for receiving and mounting the cutter on the foot lifter pivot post. The three parts are adjustably secured together by readily accessible means.

Rotatably mounted on the stamping 16 is an actuating shaft 20 having secured thereto an actuating arm 21, preferably a bell crank having one end 21a projecting to the rear as shown in FIG. 2 and normally held in the position shown therein by a spring 22 wrapped around the shaft 20, said spring having one end 22a anchored to the stamping 16 with the other end 22b bearing on a projection 23 on the arm to normally hold the arm in said raised position against a stop 16a on the stamping 16. The shaft 20 can be operated by a rotating torque input coupling 24 (FIG. l) from an operating unit, not shown, or the arm can have a usual operator (not shown) connected to an aperture 21C in the end 21a of the arm for moving the arm about the pivot.

The other end 2lb of the arm 21, as is best shown in FIG. 5, carries an operating block 25, which block slides in the forked end 26a of the blade carrier 26 for the movable blade 27. The blade carrier 26 is secured to the shaft 28 carried by the casting 17 and forms the pivot means for the movable blade 27, -as it moves into shearing relation with a fixed blade 30. The fixed blade is carried by the frame of the sewing machine at a point in back of the sewing station S as shown in FIG. 3.

As is seen in FIG. 5, the pivot means lies in a plane passing through, and is approximately in line With, the cutting edge of the fixed blade and is preferably separate and laterally displaced therefrom so that with the movable blade normally held in the raised position as shown in full lines in FIG. 5, there is a substantial unobstructed space for the passage of the material from the sewing station. This is particularly useful in an off-the-arm machine wherein the arm is usually encircled by the material being sewn so that the material is completely free -in its movement through the machine without interference with any part of the severing mechanism.

When the actuating arm 21 is moved about its pivot to the dotted position of FIG. 5, it will be noted that 3 the block slides outwardly in the forked end of the blade carrier to cause the carrier 26 for the movable blade 27 to move it about its pivot means to the dotted position wherein it is in engagement with the fixed blade 30 in a severing position.

When it is desired, therefore, to sever the chain or other material in cutting position, the actuator arm is moved from the normal position shown in FIG. 2 to the dotted position shown in FIG. 5. This causes the movable blade to be moved into severing relation with the fixed blade to shear the material disposed therebetween with a progressive shearing action, moving transversely of the xed blade and accurately severing the material quickly and expeditiously.

While the movable blade may be fixed solidly to the carrier, it is preferred to have the movable blade 27, which is preferably thin resilient cutting steel, supported at its forward end by the carrier portion 26C, with the carrier having a slight recess 26d producing a clearance extending along the blade between the carrier and blade as shown in FIGS. 3 and 7 so that the flexibility of the movable blade may be utilized during the shearing operation.

In moving to shearing position it will be noted that the movable blade carrier has a tang 3S projecting downwardly therefrom which first engages the fixed blade as the movable blade is moved into engagement therewith and, taking advantage of the floating character of the carrier, guides the movable blade into accurate relationship with the fixed blade. The tang has a slight cam shape 35a on its undersurface to insure the proper engagement of the movable blade with the fixed blade.

One advantage of the present invention resides in the fact that the movable blade can be readily removed for sharpening and when it is replaced on the carrier the enlarged holes 36 on the blade, as shown in FIG. 4 and which receive screws 37 for clamping the blade to the carrier, permit the blade to be accurately aligned with the tang 35 so that it will always engage the fixed blade with the proper engagement irrespective of the amount of material removed from the movable blade during the sharpening operation.

Another advantage of the present invention resides in the fact that the movable blade is carried by the carrier 26 which fioats and is adjustably spring loaded to provide the required shearing pressure and position between the movable blade and the fixed blade. As shown in FIG. 4, the carrier 26 is secured to the shaft 28 and has a post 40 at a point between the shaft 28 and cutting edge of the movable blade. The post projects rearwardly therefrom and passes through an outboard bearing 41 which is carried on a slidable sleeve 42 mounted on a bushing 43 adjustably threaded in the casting 17. The sleeve is limited in its movement in one direction thereon by stop ring 44 disposed on the bushing and engaging the end of the sleeve. A compression spring 45 is disposed around the post and has one end bearing against the outboard bearing 41 and the other end bearing against the carrier to yieldingly urge the carrier in the other direction to produce the proper shearing pressure in cutting position. By adjusting the bushing 43 on the casting 17, the position of the sleeve 42 and bearing 41 can be varied, thus adjusting the compression in the spring in moving the movable blade into proper shearing relation. The bushing can be locked in adjusted position by the split clamp 47.

The face-to-face engagement of the movable blade and fixed blade under the action of the compression spring 45 is controlled by the adjustment of a collar 48 on the end of the shaft 28 carrying the blade carrier, which collar engages the end of the bushing 43 in which the shaft is disposed as shown in FIG. 4.

There is a spring having one end engaging the casting and the other end secured to the post 40 which normally biases the post and connected carrier to its raised position of FIG. 5 and assists the spring 22 on the stamping 16 in this function.

Thus it will be seen that by adjusting the position of the bushing which bears against the end of the movable sleeve, having the outboard bearing, the tension in the spring can be increased or decreased, thus causing the movable blade to be moved with a greater or less yielding pressure against the fixed blade as it is moved into shearing relation and the adjustment of the collar on the shaft limits the movement of the carrier.

The proper angle of the movable blade to the fixed blade for securing the most efficient cutting can be readily adjusted by the present invention by adjusting the casting portion 17 of the base carrying the shaft 28 with respect to the stamping 16 and the bracket 18 which secures the device in position on the sewing machine frame. This is accomplished by adjusting screws 52 and 53 so as to cause the casting to rock about a vertical axis as shown in FIG. l.

When sewing heavy fabrics it may be desirable to adjust the normal position of the movable blade 27. While this may be accomplished by using a multipart adjustable actuating arm, in the herein illustrated form of the invention the block 25 is mounted on an eccentric stud means 55 (FIG. 6) so that its position can be varied on the actuating arm and thus alter the position and operation of the movable blade as required to insure full movement of the movable blade into shearing relation with the fixed blade for each operation of the actuating arm. The stud 55 has a kerf 56 by which it can be readily rotated for adjustment and locked in adjusted position by lock nut 57.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

I claim:

1. A cutting device for a sewing machine comprising a fixed blade in a plane and having a cutting edge disposed on the sewing machine in back of a sewing station therein, a base mounted on the sewing machine, a movable `blade mounted on said base and having a cutting edge for coop-eration with said fixed blade, said movable blade being unconnected to and angularly disposed with respect to said fixed blade, the movable blade being pivotally mounted on the base to pivot about an axis laterally displaced from and substantially in line with the cutting edge of the fixed blade throughout the entire shearing action, means holding the movable blade in a normal separated position from said fixed blade, means moving said blade from said normal position to engage the cutting edge of said fixed blade with a progressive shearing action, and a floating carrier having spring means yieldingly urging the movable blade in a direction perpendicular to the plane of said fixed blade into face-to-face contact with the fixed blade with a required shearing pressure during a cutting operation.

2. The invention as defined in claim 1 wherein said base comprises a plurality of parts, means adjustably joining said parts together to provide for adjusting the movable blade with respect to the fixed blade to provide for the proper normal position of the movable blade to accommodate various thicknesses of material, to provide a proper position and shear angle for the engagement of the movable blade with the fixed blade, and to provide proper shear pressure between said movable blade and fixed blade.

3. The invention as defined in claim 1 wherein said carrier is provided with means for detachably supporting and moving the movable blade, said carrier having a projecting tang engaging the fixed blade and guiding the movable blade into proper shear relation with the fixed blade upon movement of the movable blade from normal position during a cutting operation.

4. The invention as defined in claim 1 wherein said carrier is provided with means for detachably supporting and moving the movable blade and said pivot means cornis provided for varying the compression in the compression prises a pivot shaft slidably mounted on the base, said spring to control the shear pressure. carrier being secured to said pivot shaft and having a post thereon disposed between the shaft and cutting edge References Cited of he bllade, a compresioitihspring mounted o the post 5 UNITED STATES PATENTS an app ying a pressure o e carrier o move 1e carrier and pivot shaft in a direction to cause the shearing blade Issexllmour to engage the fixed blade with a desired shearing pressure, 2999473 9/1961 ann-e; 112:252

and means on the pivot rshaft for limiting the movement thereof and of the carrier in said direction.

5. The invention as dened in claim 4 wherein means 10 HERBERT F' ROSS Primary Exammer' UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION F'tent No. 3,380,417 April 30, 196s Francis P. Tamburro It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

' Column l lines 10 and ll movalbe" should read ,movable Column 4, lines 47 and 48 cancel "throughout *the entire shearing action" and insert the same after "blade" in line 55 same column 4 Signed and sealed this 9th day of September 1969.

(SEAL) Attest:

Ed'lvard M.F1ewher,1r. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents 

